Ineos has warned that Grangemouth is losing £10 million a month and will close by 2017 without fresh investment and reduced costs.

Ineos has said it is “extremely disappointed” at the lack of progress at talks this week and criticised has the inclusion of Mr Deans in the Unite delegation, saying it was "completely inappropriate" that he should be at the meeting.

Mr Halfon warned that any strike could push up fuel prices across the country.

He said: “Unions are supposed to care about the cost of living. Why are they threatening to close an oil refinery?

“This could hit petrol and diesel prices causing misery for millions of hard-pressed motorists. It’s an internal dispute. It shouldn’t lead to a strike action. They should think again.”

A Labour spokesman said: “Rather than stoking up this dispute the Conservatives should be sorting it out.

“We have talked to both the union and the employer in recent days to make clear we expect this dispute to be solved as soon as possible.”

Calum MacLean, chairman of Grangemouth Petrochemicals, who will lead the talks for the company, said: "We came to Acas in good faith and remain determined to resolve the issues facing us if at all possible.

"Unfortunately, Unite seems determined to insist on one rule for union officials and one rule for everyone else, which is completely unacceptable to the company. It also seems determined to ignore the fact that a strike could destroy Grangemouth and cause significant damage to the whole of Scotland."

Pat Rafferty Unite's Scottish secretary, hit back, saying it was "ridiculous" for the company to express disappointment at the presence of Mr Deans.

He said: "Stephen is a senior Unite representative at Ineos, a crucial part of the negotiating committee and a trusted and respected advocate of the workforce.

"Company representatives were told yesterday by Acas that if Stephen's presence created any conflict of interest then he would leave the talks. The company agreed fully with his attendance at these talks and posed no objection.

"Unite also offered through the auspices of the Acas senior conciliator a firm proposal that would end the dispute at Grangemouth and avoid damaging strikes. Ineos rejected this proposal and offered no alternatives.

"Unite has made all of the running to resolve this dispute. Ineos has offered nothing and it's getting increasingly difficult to take the company seriously."

Staff at Grangemouth have already begun shutting down the plant in readiness for the planned walkout this weekend.